The invention relates to methods and apparatus for the installation and withdrawal of submergible pumping equipment in underwater wells.
Increasing demand and price of petroleum products have greatly stimulated the sub-sea exploration for and production of oil and gas. Until recently, such activities have centered around off-shore platforms, but with the need for operating at greater depth and with greater flexibility, sub-sea wells remote from or even independent of off-shore platforms have become more attractive. Such sub-sea wells may have production trees that are remotely or automatically controlled, with production tubing extending along the ocean floor to a remote depot.
Installing and energizing submergible pumps in such sub-sea wells involve difficult problems. Running and pulling operations are expensive and should be minimized and simplified to the extent possible. The avoidance of oil spills during the running and pulling operations as well as during production pumping is a further priority. Thus, the running and pulling apparatus and also the permanent wellhead and sub-sea equipment must provide integrity against oil leakage.
Another problem area is the provision of suitable electrical energization to the motor associated with the downwell pump. Particular attention must be directed to the form of electrical connections used at the wellhead between the electrical supply cable and the suspended motor to provide adequate sealing of the components and security against oil leakage. My copending U.S. patent application Ser. No. 078,907, filed Sept. 25, 1979, now U.S. Pat. No. 4,304,452, is directed particularly towards this electrical connector aspect of sub-sea well pump and motor installations. The present invention, by contrast, is more particularly concerned with aspects concerning the running and pulling sequences for installing the pumping equipment in and withdrawing the pumping equipment from a sub-sea well, and with apparatus used for this purpose.